My list is in the order in which I visited them:
Mile High Stadium, ca 1976, for Denver Bears game.
Arlington Stadium, Texas Rangers
Gold Sox Stadium, Amarillo
Midland Angels Stadium
Whatever the Durham NC stadium was called in 1990, Durham Bulls
Dan Law Field, Lubbock Crickets
Jack Murphy Stadium, San Diego Padres
The Ballpark in Arlington, if not for weather, i prefer it multiple times more than the new Rangers park. In the mid 90's my employer had great seats, but people bitched that the March/ April games were too cold. I benefitted. LOL. Texas Rangers
Minute Maid Park/ Daiken, Houston Astros
AT&T Stadium/ Engel Field- Chattanooga Lookouts Highly recommend as a good time and good downtown area
Constellation Field, Sugarland Skeeters
OKC Redhawks and whatever stadium was called then. Fun times in Bricktown.
OneOK Field, Tulsa Drillers
Dr Pepper Ballpark, Frisco Roughriders
Oriole Park at Camden Yards. 3 Yordan dingers and blast from Correa that still hasn't landed. Astros won 23-2. Have also been to Army-Navy game in Baltimore, and their downtown Inner Harbor/ Stadium setup is awesomely walkable. I'd go back even if my teams weren't playing. Go to Fort McHenry too!!!
Rangers Cooktop Grill Stadium- I get the need for it, still haven't accepted that The Ballpark was done.
Petco Field- great downtown area and fun fans. San Diego Padres
Sutter Health Park- went to a Sacramento River Cats game last summer. Would be weird seeing the A's there now. River Cats probably a better game.
Louisville Slugger Field- saw the Bats play. Louisville downtown area is awesome. See also: bourbon everywhere. Would definitely go again.
Coors Field- great stadium in fun downtown area. Great beer options both in metro and on-premise. Hit the weather right, and it is damned near perfect for baseball. Colorado Rockies.